Heat exchanger



Nov. 4, 1952 o owrrz 2,616,530

HEAT EXCHANGER Filed Sept. 14, 1945 3 Sheets-Sheet 1 v 7 fiLf/VINDEE l/aeaw /rz.

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Nov. 4, 1952 A. HOROWITZ HEAT EXCHANGER Filed Sept. 14, 1945 Patented Nov. 4, 1952 HEAT EXCHAN GER Alexandre Horowitz, Amersfoort, Netherlands,

assignor to Hartford National Bank & Trust (30., Hartford, Conn., as trustee Application September 14, 1945, Serial No, 616,422 In Belgium June 21, 1945 (C1. BBQ-34) 8 Claims.

This invention relates to a heat exchanger and, more particularly, to means for and a method of constructing its walls whereby attachment of a partition means may be readily made to said walls.

A heat exchanger comprising channels obtained by zigzag folding of a metal strip is already known in the art. As a rule, one of the systems of channels thus obtained is traversed by one medium and the other system of channels is traversed by another medium, between which media an exchange of heat is to take place. Although very simple of construction, these exchangers generally have a drawback that it is possible, only with comparatively complicated means, to make each of the two systems communicate with the chambers out of which or into which the media concerned are flowing.

The above problem is met by the present invention. The heat exchanger according to the invention is characterized by the fact that the ends of the channels present in the exchanger are closed by folding in the end material and closing the resulting depressions which exist between the folded parts. As a rule, one or a plurality of walls serving as a partition or partitions between the chambers with which the channels communicate, adjoin the closed extremities of the channels. Folding in the material at the ends of the channels oflers the advantage that with a comparatively great width of channel there is nevertheless at the ends of the channels so much material available that the depressions which exist may be closed without great difficulty. This closing may be effected, for example, by welding or soldering, but also by utilizing artificial resins suitable for the purpose. As previously men? tioned, the partitions for the two media adjoin these closed extremities of the channels. It is possible to fasten these partitions to the channel ends either in the same operation as the closing of the ends of the c annels, or in a separate operation.

A primary object of this invention is to provide a heat exchanger device, a wall of which is constructed from a single piece of material, with a plurality of corrugations forming channels through which the heat exchanging medium may flow.

Another important object of this invention is H 2 a partitionv member by the use of bonding means filled into depressions created through a new and novel concept for closing the ends of said corrugations.

Other objects, features and advantages of this invention will be apparent as the description proceeds hereinafter.

In the drawing:

Fig. 1 is a perspective view of a plurality of corrugations bonded to a member according to the old concepts of bonding for the purpose of clearly demonstrating the improvement of the present invention over the old art.

Fig. 2 is a plan view of the corrugations shown in Fig. 1. d

Fig. 3 is a fragmentary developed view of a strip of material prepared for fabrication in accord ance with one embodiment of the invention.

Fig. 4 is an end view of the Fig. 3 structure as it is properly folded and bonded to a partition member according to the concept of the invention shown in Fig. 3.

Fig. 5 shows in plan view the structure of Fig. 3 when the strip is properly folded to produce the exposed voids or depressions at the ends of the respective channels formed by the corrugated or zigzag material.

Fi 5a i a fron e at on o the olde s rip shown in Fig. 5 as viewed from slightly above the device,

Fig. 5b is a perspective view of the same folded strip shown in Figs. 5 and 5a to more clearly show the direction of the folds.

6 is another embodiment of the present invention in a view similar to Fig. 3 in which the irregular line at an end of the developed ma terial is avoided.

Fig. 7 is a perspective view of the structure shown in Fig. 6 produced by folding the material thereof along the lines indicated.

Fig. 8 is an end view of the Fig. 6 structure showing it properly folded and bonded to a partition member.

Fig. 9 is another embodiment of the invention shown in a view similar to Figs. 3 and 6 but so planned as to avoid bonding between the previous partition means and the channel forming means of the previous structures.

Fig. 10 is an end view of Fig. 9 showing the folding of material therein to accommodate a welding bead and clamping means integral with the partition means.

Fig. 10a is a perspective view of the structure shown in Fig. 9 but folded as in Fig. 10 to more clearly show the direction of the folds.

Fig. 11 is another embodiment of the present invention produced according to a pattern of development utilized in forming a generally cylindrically shaped heater construction.

Fig. 12 is a front view of a complete heater structure using the concept of Fig. 11 as the means for joining top and bottom closure means to channel means.

Fig. 13a is a fragmentary cross-sectional view of Fig. 12 taken along the arrows A-A.

Fig. 13b is a fragmentary cross-sectional view of Fig. 12 taken along the arrows B-B.

Fig. 14 is another embodiment of the present invention in a view similar to Figs. 3, 6, 9 and 11 wherein a subspecies of the invention permits construction of a heater shown in Fig. 16.

Fig. 15 is a perspective view of the material shown in Fig. 14 when properly folded along the lines indicated by the juncture of the shadowed and light portions respectively thereof; and

Fig. 16 is a view in cross section of a heater construction formed from the structures shown in Figs. 14 and 15.

In order that the invention may be more clearly understood and readily carried into effect, it will be described more fully by reference to the aforesaid figures in the drawings.

Figs. 1 and 2 show a perspective view and a plan view of a known type of heat exchanger in which the heat-exchanging element is obtained by zigzag folding of a metal strip i. It appears from the figures that two sets of channels are thus produced which are indicated by 2 and 3 respectively. This exchanger is very simple as regards its construction, but has the drawback that it is not practicable with simple means to make the channel systems 2 and 3 adjoin the chambers with which they communicate, since the two systems must be closed relatively to each other in a gas-tight or liquid-tight manner, which can only be obtained by securing a plate 45 shown in dotted line in Fig. 1, on the end surface of the said element. This fastening causes great difliculty in practice, since for fastening the plate on the end surface of the element, for example by soldering, it would be desirable to take care of a large number of closely adjacent ends of the partitions and this can only be accomplished if the width a. of the, channels is chosen very small. Such small width of the channels causes difficulty, however, since it results in a very high resistance to the flow of the gases in the heat-exchanging element.

Referring to Figs. 3, 4 and 5 it is seen that the above-mentioned problem is overcome by first cutting out a thin, highly conductive, flat material along an irregular line at an upper end thereof as shown in Fig. 3. As shown therein, the irregularity consists of projections 46 each extending beyond the base line 41. Each pro jection 46 comprises a pair of inclined edges 48 and 49 as well as a horizontally disposed edge 50. The inclined edges 48 and 49 meet the base line 41 at points 5| and 52, respectively, and meet the horizontally disposed edges 50 at points 53 and 54, respectively. The parts 4 are separated by folding lines 55 which extend through the projections 46 and end at'the edges 50 thereof at points 56 midway of points 53 and 54. Other folding lines 51, 58, 60, 59, extending obliquely between points 5| and 68, 53 and 6|, 54 and 6|, and 52 and 68, respectively, delimit portions 5 and 6 as best shown in Fig. 3. These folding lines constitute the boundary surfaces of channels which are formed by folding in the parts 5 and B and closing the voids or depressions 4 which exist between the folded parts as will be explained more fully hereinafter.

Fig. 3 shows schematically the shade effect on the various surfaces, so that it may be seen how the folding is accomplished. This may be more readily visualized when the showing in Figs. 5 and 5a are considered in conjunction therewith. The strip being folded, has in side-view the shape shown in Fig. 4. From this it is seen that the points 5|, 53, 54, 52 of each of the projections 46 are superjacent. This condition is due to the fact that all the parts between points 5355, 5654, 5452, 525| and 5|53 of the named irregular line are of equal length and the folding lines 55, 51, 58, 59 and 60 constitute in each instance the bisector of the angles formed between points 53-56-54, 565452, 54-525|, 52'5|53 and 5|-5356. In plan view the heat-exchanging element thus obtained has the shape shown in Fig. 5. For the sake of clearness, this element is not shown fully folded in, so that the channels 1 and 8 have a width about equal to the width of the channels a of the heat-exchanger shown in Fig. 2. Since another concept underlying the invention utilizes equal width of the channels, there exists on the end surface of the exchanger considerably more material for fastening a wall to it than in the case of an exchanger of the known type. From Figs. 5a and 5b the direction of projection of the various folding portions may best be seen.

When the subject heat-exchanging element is compressed further in the process of fabrication, as is always done in practice, so that all parts of the mentioned irregular line are substantially contiguous with each other, it is possible without any difficulty, whilst retaining a sufiicient width of channel, to close the depressions by welding, solderin or similar operations, thus realizing the element as one rigid assembly.

After the strip has been folded in the manner shown, the depressions 30 must still be closed. These depressions are particularly visible in Figs. 5a and 5b. This closing may be effected by means of a soldering or welding operation whereby a closed end surface of the heat-exchanger is ob tained. After the depressions have been closed. the heat-exchanging element must have secured to it the walls serving for the separation of the chambers which the channels communicate. The depressions may be closed and the walls may be fastened, if desired, in one operation. The partition is indicated by 9 in Fig. 4. In this form of construction the end surface of the folded metal strip has provided on it a welding bead Ill serving for closing the depressions 30. On this welding bead I0 is placed the wall 9 which 's secured to the welding bead l0 by means of two welding beads and I2. The heat exchanger may exhibit different shapes; it may be straight, but also curved in shape. If the exchanger must serve as a heater in a hot-gas motor and if this heater surrounds the WOlkiIig chamber of the motor, the heat-exchanging element will be a cylinder and the wall 9 will also constitute a cylinder shell. A construction of this kind is shown in Figs. 11, 12, 13a and 13b, in which the heat exchanger is realized in this manner, but in which the heat-exchanging element is different from that in Figs. 4 and 5.

The metal strip may alternatively be given such shape that those edges of the development of the strip which must constitute the extremities of the channels are straight, as is shown in Figs. 6, 7 and 8. As before, the parts 5| '-53, 53'56'.

5 56-54', 54--52' between the folding lines at the edge of the strip are of equal length. The angles d have a value of 60. If this strip is folded .in the manner shown in Fig. 7, and similar to that shown for the strip of Figs. 5a and 5b, a heat exchanger is obtained, the side-view of which is shown in Fig. 8. For the purpose of closing the depressions 30' present between the folded parts of the strip, material serving for this purpose must be provided at the place of a surface indicated by 10 in Fig. 8'. Subsequently, the wall !3 may be fastened, for example, also by welding, to the surface H, as is also shown in Fig. 8. It will cause some difhculty in practice to close the de pressions at the place of the surface H3, so that the form of construction of the exchanger shown in Figs. 3, 4, 5, 5a and 5b will be preferred, which differs from that shown in Figs. 6, 7 and 8 solely in that the cross-hatched portion bounded by surfaces 10, I! of the walls 4 of the heat-exchangl51314, respectively. Referring to Fig. 9 it is seen that the top of the strip material is cut out to form an irregular line for instance, composed of the contour T3'|4T5l3-lel5, the upwardly protruding portions being made to have equal sides but being comparatively longer in dimension than the intervening portion IE-13. The mid points of each of the protruding portions 13l4-l5 are respectively on the line forming the base of the convolutions in each corrugation or zigzag. The strip material is first folded along vertical lines such as 'l41 6 in alternating directions (see Fig. 100.) to arrive at a corrugated structure as was formed for the embodiment of the invention comprising, for example, Figs. 3, 4, 5, 5a and 5b. The mentioned protruding portions are additionally folded along lines such as 73-16 and 'l5l6 in such a manner that the protruding portions are pushed over the tops or ends of the channels formed by the corrugated material as shown at M in Fig. 10a. It can be readily seen that this general plan of closing the ends of the channels will produce overhanging ledges or hook-shaped projections Id and !5 as shown in Fig. 10. However, these projections will also contain upwardly facing depressions or voids similar to voids or depressions 3d described'hercinbefore and these depressions may be utilized for the retention of bonding or welding material which when built up properly can be formed into a portion IE to form a continuation of the mentioned ledge like structure. This portion or member I8 integrated with the strip material can be utilized for a part of a gripping means to be described now.

The partition between the chambers with which the two systems of channels communicate is here constituted by a wall 16 consisting of two halves Ida and Ifib, a bent edge of each of which engages behind the projections l4 and iii. The two wall halves Mia and I6?) are fastened together by means of rivets I1. Before the wall I5 is provided, the end surface of the heat-exchangin element is closed by means of an amount of solder it. This particular form of construction is readily adapof channels from each other.

6 table for use in a heater construction because the bonding or soldering of the mentioned depressions with a suitable material for closing these depressions may be done independently of the process of attaching a partition wall to the fabricated strip material.

Figs. 11, 12, 13a and 131) show another form of construction of the heat-exchanger according to the invention. Fig. 11 shows a development of the heat-exchanging element and Fig. 12 is a sectional view of the complete heat-exchanger, while Figs. 1.3a and 131) show the cross-sections A-A and B-B of the exchanger in Fig. 11. Referring to Fig. 11 it is seen that a fragmentary strip of material similar to the strip 4 of Fig. 3 having similar protruding portions is used. However, since the strip material of Fig. 11 is to h formed. after the usual corrugating process of the same to a generally cylindrical form for utilization in a cylindrical type heater both the top and bottom end portions of the strip material must he additionally out along an irregular line 31. The extreme top and bottom portions of these mentioned end portions are of equal length and they are tipped either downwardly or upwardly depending upon their position in the material and the protruding portions are folded along lines 19 and 30 originating from points such as T! and 18 for folding in a manner similar to that already described for Fig. 3 and Fig. 6. From the previous description of the invention it is believed to be clear that when the voids formed by these folded protruding portions are filled up a bead such as a welding bead l9 similar to portion ll! of Fig. 10 can be produced and which. of course, separate the two systems The wall 20 serving for separating the chambers with which the two systems of channels communicate adjoins the said welding bead I9. The cover 20 has a conical boundary surface 2| which is fastened to that surface of the welding bead 49 which is adjacent to the exterior by means of a welding bead 22 of triangular section. At the bottom of the exchanger the conical end surface of the heatexchanging element is closed by means of a welding bead 23 to which adjoins the partition 24 which is secured to the outside of the welding bead 23 by means of two welding beads 25 and 25. From Fig. 13a it appears the folded parts of the broken line, which constitute the bound ary of the strip of material, closely engage one another, so that the welding bead 19 may be provided on them without difiiculty. From Fig. 11 it follows that the points of intersection 11 and lB of the folding lines between the strip parts which jointly constitute the closure of the channels are not in coincidence. due to which ex .cessive mechanic .load on the points 1! and 18 in providing the folds is avoided. Fig. 1319 shows that, although at the edges of the heat-exchanging element the parts of the irregular line when folded as suggested, are substantially contiguous to each other, the channels for the passage of the medium may nevertheless have a comparatively great width.

The heat exchanger shown is intended as a heater fora hot-gas motor, the portion 2'! surrounding the working chamber of the motor. In this form of construction the walls of the heatexchanging element have protuberances 28 pro- 'vided on them in such manner that their extremities contact with the extremities of the otherprotuberances 28 provided on the adjacent "wall. This can particularly be seen from Fig.

13b; The walls of the exchanger are thus supported in a simple manner and it is ensured that the walls of the exchanger are not deformed owing to the difference in pressure which exists between the gases in the two channel systems. If desired, the walls of the exchanger may also have provided on them ridges or similar parts (not shown) serving for guiding the gases flowing along the walls.

' Figs. 14 and 15 show still another form of construction of the heat-exchanging element in the developed state and in the folded state respectively. The folded parts 29 constitute in this case the top closures of the channel system the channels of which are indicated by 40 in Fig. 15. The channels 3| are not closed at the top. In order to obtain a closure of the two channel systems relatively to each other, a welding bead 33 shown in dotted line in Fig. 15 may be provided on the edges 32 of the parts folded in. For the sake of clearness the widths of the channel systems and 3| are indicated Fig. 15 on an enlarged scale. It is evident that, when the heat-exchanging element has been folded in to a greater extent, the provision of the welding bead 33 may take place without difficulty, the welding bead then being band-shaped. If the heat-exchanging element has to form part of an exchanger of heat for a hot-gas motor which surrounds the working chamber of the motor,

the welding bead 32 constitutes a cylindrical band surrounding the heat-exchanging element. Another application of the heat-exchanging element of Figs. 14 and 15 is still imaginable, name- 1y, that in which this element is fastened, for example by soldering, to a plane wall 35, in order thus to increase the heat-absorbing and heatemitting capacity respectively of this wall. This is shown diagrammatically in Fig. 16. The walls through which the exchange of heat must take place forms part of a cylindrical body, which is not shown in the drawing. The exchanger shown in Fig. 15 is soldered on the outside of the said body in the form of a rim. The channels indicated by 3| in Fig. 15 are not active, so that their walls can as well directly engage one another. The ends of the channels 30 are closed by folding in in the manner shown in Fig. 15. On the outside they are closed by means of welding beads 36. Further, the heat-exchanging element is surrounded by a cylindrical band 31 in such manner that slits 38 and 39 exists for the admission and the discharge of the media between the welding beads 36 and the band 31.

The medium is circulating in the manner indicated by the arrows. The chambers containing the medium flowing through the heat-exchanging element before and after traversing the latter are separated by means of a plate 40 which adjoins the band 31.

What I claim is:

1. A corrugated wall comprised of a blank with at least a top irregular line before its folding, said corrugated wall being angularly folded along main folding lines which are substantially parallel to each other to form wall portions running in zigzag relationship to each other, each of said folding lines being substantially equally spaced from two adjacent folding lines and extending to said top irregular line, parts of the ends of said angularly folded corrugations adjacent said top irregular line being compoundly folded at predetermined angles to form re-entrant depressions each received between two adjacent of said wall portions and alternately dis- 8 posed in opposite directions, bonding means filling a substantial portion of said alternately disposed depressions to form a fiat surfaced exterior bead, and partition means coupled to said bead.

2. A zigzag shaped wall with preformed top and bottom irregular edges, the outermost portions of said edges forming the base line of equilateral triangles each having an apex on alternate zigzag folding lines of said wall, projections on said irregular edges located between said outermost portions and having their apexes on the intermediate folding lines located between the first said foldin lines, the channels of said zigzag wall being obturated at the ends thereof by folding said triangles of material over the same and reversely folding strip material contiguous to said triangles along lines convergin inwardly of each said apex, said latter folding producing stepped and converging slopes; bonding material covering said slopes to produce even generally cone-shaped beads; and end-wall forming means coupled to said zigzag wall.

3. A heat exchanger comprising adjacent channels obtained by zigza folding of a metal strip, end material integral with said strip multiply folded in over the ends of each of said channels to form zigzag enclosing members, said folded end material each having a plurality of outwardly facing voids, and bonding material within said voids forming a welding bead to retain any desired body.

4. A heat exchanger as claimed in claim 3 wherein the edges of a development of the zigzag folded strip constituting the end extremities of said channels exhibits the shape of an irregular line, the folding lines for each zigzag formation constituting the bisector of the angle which exists within the adjacent parts of the said folded end material.

5. A heat exchanger comprising zigzag folded strip with a preformed irregular perimeter forming adjacent channels, the end material of said strip being reversely and multipl folded along pairs of converging lines at equal angles to the folds of said zigzag folded strip adjacent the irregular portion of said strip to form closure means for each of said channels, said multiple folding creating a plurality of outwardly facing depressions at the end of each channel, a head of distinct welding material Within said depressions and partition means bonded to said end material, corresponding parts of said irregular perimeter being of equal length.

6. A heat exchanger as claimed in claim 5 wherein said converging folding lines in the strip parts which jointly constitute the closure of any one channel do not all pass through one point.

7. A heat exchanger as claimed in claim 5 wherein a number of small depressions in said strip along sections thereof form the walls of said channels to provide proper spacing and strengthening of said walls.

8. A heat exchanger comprising a wall through which heat is to be transmitted, said wall being folded in a zigzag manner to provide main angularly related partitions forming adjacent channels on either side of said folded wall, each fold line of said folded wall having two pairs of longitudinally-spaced divergent fold lines extending therefrom to the end of the wall, the fold line being reversely folded between its points of intersection with the divergent fold lines to form separate groups each comprising a plurality of smaller partitions cooperating to obturate each of said ends of said channels, the total number of said smaller partitions comprised in all said groups being more than twice the number of all said file of this patent:

UNITED STATES PATENTS mam partitions Number Name Date 1,206,717 Kochling Nov. 28, 1916 ALEXANDRE HOROWITZ- 5 1,444,480 Patch Feb. 6, 1923 1,472,863 Bingay Nov. 6, 1923 FEFERENCES CITED 1,516,694 Atkinson Nov. 25, 1924 The followmg references are of record in the 11303330 Eaton Nov. 30, 1926 

